Weird `<const host: bool = true>` generics popping in beta docs

[a1phyr]

Examples include:

• https://doc.rust-lang.org/beta/core/ptr/struct.NonNull.html#method.dangling
• https://doc.rust-lang.org/nightly/core/cell/struct.OnceCell.html#method.new
• Most of https://doc.rust-lang.org/nightly/core/net/struct.Ipv6Addr.html

This is probably related to the recent addition of #[rustc_host].

[GuillaumeGomez]

Thanks for opening this issue! I'll take a look as soon as I can.

[a1phyr]

Fixed by #116670 and #116856